Interpretive Summary: DNA barcodes are short pieces of genetic material that function as unique species identifiers. They are very useful for identifying very closely related animal species that cannot be distinguished by conventional methods, for example by differences in external physical characteristics. Since the genetic material is subject to mutation and other processes that can alter DNA sequences, it is important to be sure that barcodes are sufficiently invariant that they can be reliably linked to a given species. Barcodes have been derived for several important insect pest groups, but for very few insect natural enemies. We derived DNA barcodes for five species of ladybird beetles, including two that are very similar in appearance, that are important natural enemies of insect pests in North American crops. Barcodes were sufficiently unique to unequivocally identify all five species, including the two closely related ones, with all sequences of a given species being at least 99% identical. These barcodes will be used by scientists to ensure that ladybird beetles are correctly identified during field research, thereby helping to determine which species are most effective in controlling insect pests, and hence most worthy of conservation by crop management practices. They will also be used by taxonomists to understand the evolutionary relationships of this important group of natural enemies.

Technical Abstract:
DNA barcodes have proven invaluable in identifying and distinguishing insect pests, for example for determining the provenance of exotic invasives, but relatively few insect natural enemies have been barcoded. We used Folmer et al.’s universal invertebrate primers (1994), and those designed by Hebert et al. (2004) for lepidopterous insects, to amplify 710 or 648 bp at the 5’ end of the mitochondrial cytochrome oxidase c subunit I (COI) gene in five species of ladybird beetles from wheat, sorgum, and cotton fields in six states in the U.S. Plains and Midwest: three native species, Hipodamia convergens, H. parenthesis, and Coleomegilla maculata; and and two exotic species, Harmonia axyridis and Coccinella septempunctata. Variabilities within clades of each species were extremely low, ranging from 0.0 to 0.8% (Kimura 2-parameter distances), and there were no instances of sequence overlap among species. These data support the general utility of COI barcodes for this important natural enemy group, and will aid systematists in unraveling the relationships of these species, for some of which the systematics is in flux.